Aggressive Cyclin D1 Negative Blastoid Variant Mantle Cell Lymphoma-A Case Report.

A 68-year-old male presents with generalized lymphadenopathy and fever of short duration. Axillary lymph node excision was performed and was sent for histopathological evaluation. Microscopic evaluation of the submitted lymph node revealed diffuse proliferation of intermediate-sized atypical lymphoid cells with round nuclei, irregular membranes, finely dispersed chromatin, and inconspicuous nucleoli. Mitotic figures were frequently seen. Immunohistochemical evaluation revealed diffuse expression of CD20, CD5, CD10, B-cell lymphoma 2 (Bcl2), and B-cell lymphoma 6 (Bcl6). Atypical lymphoid cells were negative for cyclin D1; however, showed diffuse and strong nuclear expression of SOX11. MIB1 proliferation index was high (Ki67: 90%-95%). Based on morphological features and immunohistochemical findings a diagnosis of "cyclin D1 negative aggressive blastoid variant of mantle cell lymphoma (MCL)" was offered. The classic morphology of MCL is seen in 90% of cases, while the remaining (∼10%) are considered as variants. A blastoid variant is an aggressive subtype that can lack expression of CD5 as well as cyclin D1, but instead expresses CD10, Bcl6, and CD23. SOX11 expression is seen in 90% cases of MCL and in almost 100% cases of cyclin D1 negative MCL. The current case highlights the unusual morphologic and aggressive variant of MCL and a significant role of SOX11 in its diagnosis.